A reduction in computational load associated with correction of repeatable runout is provided. Rather than performing DFT for each analyzed frequency at each interrupt, at least some frequencies are not analyzed in the same interrupt period. DFTs for different frequencies may be staggered or interleaved. DFTs for different frequencies may be performed at different rates, preferably, using higher rates for higher frequencies.
Legal claims defining the scope of protection, as filed with the USPTO.
1. Apparatus usable in a data storage device having at least one rotatable disk having at least a first plurality of tracks defined thereon and at least one positionable head, each of said first plurality of tracks including indicators defining a plurality of sectors, the apparatus comprising: at least a first controllable actuator for positioning said head relative to a selected track; circuitry configured to: receive a first signal which is related to tracking of said head; determine at least a first value related to at least a first characteristic of at least first and second different frequency components of said first signal, wherein, during transit of at least one of first and second sectors, said first characteristic is determined for said first frequency component without determining said first characteristic for said second frequency component; and use said first value in controlling tracking to correct repeatable runout.
2. Apparatus as claimed in claim 1 wherein said data storage device is a magnetic disk drive.
3. Apparatus as claimed in claim 1 wherein said first signal comprises a position error signal.
4. Apparatus as claimed in claim 1 wherein said circuitry comprises a programmed microprocessor.
5. Apparatus as claimed in claim 1 wherein said first value comprises an adaptive runout correction feed-forward value.
6. Apparatus as claimed in claim 1 wherein said first characteristic comprises an indication of the magnitude of power of a frequency component of said first signal.
7. Apparatus as claimed in claim 1 wherein said first characteristic is determined using a discrete Fourier transform.
8. Apparatus as claimed in claim 1 wherein said first and second frequencies are integral multiples of said disk's frequency of rotation.
9. Apparatus as claimed in claim 1 wherein said circuitry is configured to repeat determination of said first characteristic of said first frequency component of said first signal, to define a first average rate, for determination for said first frequency component, and to repeat determination of said first characteristic of said second frequency component of said first signal, to define a second average rate, for determination for said second frequency component, and wherein said first rate is different from said second rate.
10. Apparatus as claimed in claim 1 wherein said first characteristic is determined at a plurality of different rates, for a plurality of different frequency components of said first signal.
11. Apparatus as claimed in claim 10 wherein said plurality of rates is defined in a table.
12. Apparatus as claimed in claim 10 wherein said plurality of rates are initially defined during manufacture of said data storage device and stored therein.
13. Apparatus as claimed in claim 10 wherein said circuitry is configured to update said plurality of rates periodically.
14. Apparatus as claimed in claim 10 wherein said circuitry is configured to update said plurality of rates in response to sensing of a change in at least one of environmental conditions, computational loads or error rates.
15. Apparatus as claimed in claim 10 wherein a rate for a given frequency component of said first signal is at least as large as a rate for a lower-frequency component of said first signal.
16. A method usable in a data storage device having at least one rotatable disk having at least a first plurality of tracks defined thereon and at least one positionable head, each of said first plurality of tracks including indicators defining a plurality of sectors, and at least a first controllable actuator for positioning said head relative to a selected track, the method comprising: receiving a first signal which is related to tracking of said head; determining at least a first value related to at least a first characteristic of at least first and second different frequency components of said first signal; wherein, during transit of at least one of first and second sectors, said first characteristic is determined for said first frequency component without determining said first characteristic for said second frequency component; and using said first value in controlling tracking to correct repeatable runout.
17. A method as claimed in claim 16 wherein said data storage device is a magnetic disk drive.
18. A method as claimed in claim 16 wherein said first signal comprises a position error signal.
19. A method as claimed in claim 16 wherein said step of determining and using are performed using a programmed microprocessor.
20. A method as claimed in claim 16 wherein said first value comprises an adaptive runout correction feed-forward value.
21. A method as claimed in claim 16 wherein said first characteristic comprises an indication of the magnitude of power of a frequency component of said first signal.
22. A method as claimed in claim 16 wherein said first characteristic is determined using a discrete Fourier transform.
23. A method as claimed in claim 16 wherein said first and second frequencies are integral multiples of said disk's frequency of rotation.
24. A method as claimed in claim 16 further comprising: repeating determination of said first characteristic of said first frequency component of said first signal, to define a first average rate, for determination for said first frequency component; repeating determination of said first characteristic of said second frequency component of said first signal, to define a second average rate, for determination for said second frequency component; wherein said first rate is different from said second rate.
25. A method as claimed in claim 16 wherein said first characteristic is determined at a plurality of different rates, for a plurality of different frequency components of said first signal.
26. A method as claimed in claim 25 wherein said plurality of rates is defined in a table.
27. A method as claimed in claim 25 wherein said plurality of rates are initially defined during manufacture of said data storage device and stored therein.
28. A method as claimed in claim 25 further comprising updating said plurality of rates periodically.
29. A method as claimed in claim 25 further comprising updating said plurality of rates in response to sensing of a change in at least one of environmental conditions, computational loads or error rates.
30. A method as claimed in claim 25 wherein the rate for a given frequency component of said first signal is at least as large as the rate for a lower-frequency component of said first signal.
31. Apparatus usable in a data storage device having at least one rotatable disk having at least a first plurality of tracks defined thereon and at least one positionable head, each of said first plurality of tracks including indicators defining a plurality of sectors, and at least a first controllable actuator for positioning said head relative to a selected track, the method comprising: means for receiving a first signal which is related to tracking of said head; means for determining at least a first value related to at least a first characteristic of at least first and second different frequency components of said first signal wherein, during transit of at least one of first and second sectors, said first characteristic is determined for said first frequency component without determining said first characteristic for said second frequency component; and means for using said first value in controlling tracking to correct repeatable runout.
32. Apparatus as claimed in claim 31 wherein said data storage device is a magnetic disk drive.
33. Apparatus as claimed in claim 31 wherein said first signal comprises a position error signal.
34. Apparatus as claimed in claim 31 wherein said means for determining and said means for using comprise a programmed microprocessor.
35. Apparatus as claimed in claim 31 wherein said first value comprises an adaptive runout correction feed-forward value.
36. Apparatus as claimed in claim 31 wherein said first characteristic comprises an indication of the magnitude of power of a frequency component of said first signal.
37. Apparatus as claimed in claim 31 wherein said first characteristic is determined using a discrete Fourier transform.
38. Apparatus as claimed in claim 31 wherein said first and second frequencies are integral multiples of said disk's frequency of rotation.
39. Apparatus as claimed in claim 31 further comprising: first means for repeating determination of said first characteristic of said first frequency component of said first signal, to define a first average rate, for determination for said first frequency component; and second means for repeating determination of said first characteristic of said second frequency component of said first signal, to define a second average rate, for determination for said second frequency component; wherein said first rate is different from said second rate.
40. Apparatus as claimed in claim 39 wherein said first and second means comprise a programmed microprocessor.
41. Apparatus as claimed in claim 31 wherein said first characteristic is determined at a plurality of different rates, for a plurality of different frequency components of said first signal.
42. Apparatus as claimed in claim 41 wherein said plurality of rates is defined in a table.
43. Apparatus as claimed in claim 41 wherein said plurality of rates are initially defined during manufacture of said data storage device and stored therein.
44. Apparatus as claimed in claim 41 further comprising means for updating said plurality of rates periodically.
45. Apparatus as claimed in claim 44 wherein said means for updating comprises a programmed microprocessor.
46. Apparatus as claimed in claim 41 further comprising means for updating said plurality of rates in response to sensing of a change in at least one of environmental conditions, computational loads or error rates.
47. Apparatus as claimed in claim 41 wherein the rate for a given frequency component of said first signal is at least as large as the rate for a lower-frequency component of said first signal.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 8, 2004
August 1, 2006
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